Kinetic characterization of glycogen phosphorylase B from skeletal muscle of the mullet Liza ramada.
1. Glycogen phosphorylase purified from muscle of mullet (Liza ramada) has been kinetically characterized. 2. Kinetic analysis for the substrates glucose-1-P and glycogen showed no homotropic co-operativity. AMP exhibited only a slight homotropic co-operative behaviour, although it caused a decrease in the Km for glucose-1-P. 3. Glucose, ATP and glucose-6-P behaved as phosphorylase b inhibitors. Kinetic analysis of the inhibition showed the characteristic heterotropic effect both for the substrate glucose-1-P and the activator AMP. 4. However, glucose-6-P, which enhances the co-operativity between AMP molecules, lost its heterotropic effect on the glucose-1-P saturation curve.
Bonamusa
L
L
Unitat de Bioquímica, Facultat de Farmácia, Universitat de Barcelona, Spain.
Baanante
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IV
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000494:Allosteric Regulation; D000818:Animals; D005947:Glucose / Q000494:pharmacology; D019298:Glucose-6-Phosphate; D005958:Glucosephosphates / Q000494:pharmacology; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010473:Perciformes / Q000378:metabolism*; D006005:Phosphorylases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity
D005958:Glucosephosphates; D000249:Adenosine Monophosphate; D019298:Glucose-6-Phosphate; D000255:Adenosine Triphosphate; C031590:glucose-1-phosphate; D006005:Phosphorylases; D005947:Glucose